Mutual Group Polarization in the Blogosphere: Tracking the Hoax Discourse on Climate Change (2020)


A salient tactic used in online communication about anthropogenic climate change is to accuse the opposite side of being untruthful. This hoax discourse identifies one side as deniers of scientific facts and the other side as manufacturing false alarm. We study the hoax discourse on climate change in the English-speaking blogosphere as a disruptive discursive practice. The study uses automated, qualitative, and quantitative content analysis as well as network analysis to identify the main patterns of the hoax discourse, drawing on a sample of almost 50,000 blog posts related to climate change published online for one year, from May 14, 2016, to May 14, 2017. The study shows that hoax discourses are a salient feature of online debates. They engage both mainstream voices and contrarians in mutual accusations. Accusations of untruthfulness are rarely voiced in a way that identifies concrete lies and liars; instead, they form part of broad attacks designed to vilify the other group. The discourse does not directly address the other side of the debate. It does not constitute a deliberation, but rather serves to affirm one’s social group identity and exacerbate mutual group polarization.

Brüggemann, Michael; Elgesem, Dag; Bienzeilser, Nils; Dedecek Gertz, Helena; Walter, Stefanie (2020): Mutual Group Polarization in the Blogosphere. Tracking the Hoax Discourse on Climate Change. In International Journal of Communication 14, pp. 1025–1048. Available online at

Scientific networks on Twitter: Analyzing scientists’ interactions in the climate change debate (2019)

Scientific issues requiring urgent societal actions—such as climate change—have increased the need for communication and interaction between scientists and other societal actors. Social media platforms facilitate such exchanges. This study investigates who scientists interact with on Twitter, and whether their communication differs when engaging with actors beyond the scientific community. We focus on the climate change debate on Twitter and combine network analysis with automated content analysis. The results show that scientists interact most intensively with their peers, but also communication beyond the scientific community is important. The findings suggest that scientists adjust their communication style to their audience: They use more neutral language when communicating with other scientists, and more words expressing negative emotions when communicating with journalists, civil society, and politicians. Likewise, they stress certainty more when communicating with politicians, indicating that scientists use language strategically when communicating beyond the scientific community.

Walter, Stefanie; Lörcher, Ines; Brüggemann, Michael (2019): Scientific networks on Twitter: Analyzing scientists’ interactions in the climate change debate. In Public Understanding of Science, 696-712. Available online at

Klimapolitik in den Medien – Das Publikum erwartet mehr. Befunde einer Befragung zu den UN-Klimagipfeln 2015 und 2018 (2019)


In einer Rezipientenbefragung wurden die Nutzung und
Bewertung der Berichterstattung zu den UN-Klimagipfeln 2015
und 2018 verglichen. Das öffentlich-rechtliche Fernsehen ist die wichtigste Quelle, um etwas über den Klimawandel zu erfahren, gefolgt von Privatsendern, Radio und Onlinemedien. Ein Großteil der Befragten hält die Berichte in den Medien für verständlich, wünscht sich aber eine ausführlichere Berichterstattung. Auch die Bedeutung der Anschlusskommunikation hat im Vergleich der beiden Jahre zugenommen. Immer mehr Menschen sprechen mit Freunden und Familie über den Klimawandel.

De Silva-Schmidt, Fenja; Brüggemann, Michael (2019): Klimapolitik in den Medien – Das Publikum erwartet mehr. Befunde einer Befragung zu den UN-Klimagipfeln 2015 und 2018. In Media Perspektiven (3), pp. 107–113. Available online at

Echo Chambers of Denial: Explaining user comments on climate change (2018)


Although there is a broad consensus among scientists and journalists about the existence of anthropogenic climate change as a global problem, some segments of the population remain doubtful about the human impact on it. The internet provides citizens with opportunities to publicly voice their doubts and user comment sections of online media are popular form of user-generated content. This study identifies factors that foster comments that are sceptical or supportive of basic assumptions of anthropogenic climate change, drawing on online news in the US, the UK, Germany, India, and Switzerland. The results show that users adapt to the dominant opinion within the respective media outlet: user comment sections serve as echo chambers rather than as corrective mechanisms. Climate change denial is more visible in user comment sections in countries where the climate change debate reflects the scientific consensus on climate change and user comments create niches of denial.

Walter, Stefanie; Brüggemann, Michael; Engesser, Sven (2017): Echo Chambers of Denial. Explaining User Comments on Climate Change. In Environmental Communication: A Journal of Nature and Culture 12 (2), pp. 204–217. Available online at

From “Knowledge Brokers” to Opinion Makers: How Physical Presence Affected Scientists’ Twitter Use During the COP21 Climate Change Conference (2018)


Professional norms of science have played an important role in discouraging scientists from raising their voices in public. However, they are increasingly using social media to discuss and publicize their research. This study investigates the 2015 United Nations Climate Change Conference summit and examines scientists’ social media use by analyzing “digital traces” that scientists left on social media during the summit. Using geolocated tweets, we compare the Twitter use of scientists who attended the conference with those who did not. Combining automated, quantitative, and qualitative content analysis, the study shows how scientists participating in the conference provided live reporting and formed a transnational network. Scientists at the conference and elsewhere engaged in political advocacy, indicating a shift toward a new pattern of hybrid science communication, which includes characteristics that have formerly been attributed to journalism and advocacy.

Walter, Stefanie; De Silva-Schmidt, Fenja; Brüggemann, Michael (2017): From “Knowledge Brokers” to Opinion Makers. How Physical Presence Affected Scientists’ Twitter Use During the COP21 Climate Change Conference. In International Journal of Communication 12, pp. 1–22. Available online at

Opportunity makes opinion leaders: Analyzing the role of first-hand information in opinion leadership in social media networks (2018)


Theorizing information flows is at the heart of traditional communication theories such as the two-step flow of communication and the concept of opinion leadership. Social media have fundamentally altered how information reaches people. This study examines opinion leadership in social media networks and argues that opinion leaders may no longer need to rely on information provided by the media if they have access to first-hand information. To test this assumption empirically, we used data from the 2015 United Nations Climate Change Conference (COP21). Attendees of the conference had direct information about what was happening, which they were able to share live with their followers via social media. We used geo-located tweets to identify Twitter users who attended the COP21 summit. We then located these users in a data set of tweets that were collected based on the main conference hashtag (#COP21) and represent the wider social media debate on the conference. Our results, which are based on network analysis measures and Twitter user data, show that COP21 participants were more central actors compared to the average user in the network, and that they were more likely to have brokering positions. They were also more involved in the debate and received more attention from other users. We used automated content analysis to divide COP21 participants into different actor types and performed the analysis by actor group. The results show only minor differences across the actors and support the robustness of our analysis.

Walter, Stefanie; Brüggemann, Michael (2018): Opportunity makes opinion leaders. Analyzing the role of first-hand information in opinion leadership in social media networks. In Information, Communication & Society, pp. 1–21. Available online at

Diverging worlds of foreign correspondence: The changing working conditions of correspondents in Germany, Austria, and Switzerland (2017)


Foreign correspondents seem to have become an endangered species. They are said to be increasingly substituted by new forms of foreign correspondence. These claims are often raised by researchers studying foreign correspondence to and from the United States and the United Kingdom. We test whether assumptions about the demise and substitution of the traditional foreign correspondent also apply beyond these contexts. Particularly, the study seeks to explore the differences in the working conditions of various kinds of foreign correspondents. Based on 211 responses gathered through an online survey of a carefully reconstructed population of 721 journalists, it describes the profile and working conditions of foreign correspondents in Germany, Switzerland, and Austria. It finds that the traditional correspondent – a professional journalist working full-time for legacy media – may be more resistant to change than expected. In the perception of correspondents, there is not much substitution through parachutes, locals, amateurs, or reporting from the headquarters. Working conditions are not worsening for everyone. Rather, we find diverging worlds of foreign correspondence depending on the media type, the country of origin, and the kind of job contract journalists have.

Brüggemann, Michael; Keel, Guido; Hanitzsch, Thomas; Götzenbrucker, Gerit; Schacht, Laura (2017): Diverging worlds of foreign correspondence. The changing working conditions of correspondents in Germany, Austria, and Switzerland. In Journalism 18 (5), pp. 539–557. Available online at

Beyond false balance: How interpretive journalism shapes media coverage of climate change (2017)


This study explores two pre-eminent features of transnational media coverage of climate change: The framing of climate change as a harmful, human-induced risk and the way that reporting handles contrarian voices in the climate debate. The analysis shows how journalists, and their interpretations and professional norms, shape media debates about climate change. The study links an analysis of media content to a survey of the authors of the respective articles. It covers leading print and online news outlets in Germany, India, the United Kingdom, the United States, and Switzerland. It finds that climate journalism has moved beyond the norm of balance towards a more interpretive pattern of journalism. Quoting contrarian voices still is part of transnational climate coverage, but these quotes are contextualized with a dismissal of climate change denial. Yet niches of denial persist in certain contexts, and much journalistic attention is focused on the narrative of ‘warners vs. deniers,’ and overlooks the more relevant debates about climate change.

Brüggemann, Michael; Engesser, Sven (2017): Beyond false balance. How interpretive journalism shapes media coverage of climate change. In Global Environmental Change 42, pp. 58–67. Available online at

The Appeasement Effect of a UN Climate Summit on the German Public (2017)


The annual UN climate summits receive intense global media coverage, and as such could engage local publics around the world, stimulate debate and knowledge about climate politics, and, ultimately, mobilize people to combat climate change. Here we show that, in contrast to these hopes, although the German public were exposed to news about the 2015 Paris summit, they did not engage with it in a more active way. Comparing knowledge and attitudes before, during and after the summit using a three-wave online panel survey (quota sample, N = 1121), we find that respondents learnt a few basic facts about the conference but they continue to lack basic background knowledge about climate policy. Trust in global climate policy increased a little, but citizens were less inclined to support a leading role for Germany in climate politics. Moreover, they were not more likely to engage personally in climate protection. These results suggest that this global media event had a modest appeasing rather than mobilizing effect.

Brüggemann, Michael; De Silva-Schmidt, Fenja; Hoppe, Imke; Arlt, Dorothee; Schmitt, Josephine B. (2017): The appeasement effect of a United Nations climate summit on the German public. In Nature Climate Change 7 (11), pp. 783–787. Available online at

Download: Final accepted manuscript including appendix

Climate Engagement in a Digital Age: Exploring the Drivers of Participation in Climate Discourse Online in the Context of COP21 (2017)

Various scholars underscore the importance of public engagement with climate change to successfully respond to the challenges of global warming. However, although online media provide various new opportunities to actively engage in climate discourse so far very little is known about the drivers of this form of engagement. Against this background, this study tested a theoretical model on the effects of media and interpersonal communication on participation in climate discourse online using data from a representative online survey of German citizens (n = 1392) carried out while COP21. Overall, the results show that receiving information on climate change from social media (social networks, Twitter, blogs), active information seeking online and interpersonal conversations about COP21 strongly encourage participation in climate discourse online. Moreover, results provide relevant insights on the role of interest in climate politics, personal issue relevance and climate scepticism as preconditions of communication effects.

Arlt, Dorothee; Hoppe, Imke; Schmitt, Josephine B.; De Silva-Schmidt, Fenja; Brüggemann, Michael (2017): Climate Engagement in a Digital Age. Exploring the Drivers of Participation in Climate Discourse Online in the Context of COP21. In Environmental communication 49 (3), pp. 84–98. Available online at